Funding for the work described herein was provided in part by the Federal government, which has certain rights in the invention.
The invention relates to transgenic non-human mammals that develop Tau pathologies.
Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is characterized clinically by behavioral, cognitive, and motor disturbance. Historically, many cases of this disease have been described as Pick""s disease. In the majority of families described to date, personality change is the presenting symptom, with initial behavioral changes accompanied by progressive cognitive impairment and sometimes parkinsonism. At autopsy, all patients with FTDP-17 display pronounced fronto-temporal atrophy and neuronal cell loss, gray and white matter gliosis, and superficial cortical spongiform changes. More variably, ballooned neurons, or Pick""s cells, are present. In addition, most FTDP-17 cases show neuronal and/or glial inclusions that stain positively with antibodies raised against the microtubule associated protein Tau, although the Tau pathology varies considerably in both its quantity (or severity) and characteristics. Patients with FTDP-17 do not have Lewy bodies or, crucially, Pick bodies, which distinguishes them from classical Pick""s disease cases. The disease is inherited as an autosomal dominant trait with age dependent penetrance. The age of onset can be highly variable but is usually between the ages of 45-65 years.
The invention is based on the discovery of mutations in the tau gene that are linked to Tau pathologies. Thus, the invention provides nucleic acid molecules that include such mutations, allowing animal models of neurodegenerative diseases to be developed. Identification of the mutations also provides methods for determining a diagnosis of neurodegenerative disease in a patient.
The invention features an isolated nucleic acid molecule including a tau gene sequence, wherein the molecule has a mutation linked to a Tau pathology. The nucleic acid molecule can be from about 15 nucleotides in length to full-length. The mutation can be located in an exon or in an intron. A mutation can be in exon 7, exon 9, exon 10, or in exon 13, and in particular embodiments, at a region encoding amino acids 152, 257, 272, 301, 389, or 406. In one embodiment, the mutation at amino acid 152 is a change from an alanine to a threonine residue, the mutation at amino acid 257 is a change from a lysine to a threonine residue, and the mutation at amino acid 272 is a change from a glycine residue to a valine residue. The mutation at amino acid 301 can be a change from a proline residue to a leucine residue. The mutation at amino acid 389 can be a change from a glycine to an arginine residue. The mutation of amino acid 406 can be a change from an arginine to a tryptophan residue. An additional mutation can include deletion of amino acid 280. The mutation also can be in a splice donor site region and, in a particular embodiment, can destabilize a stem-loop structure of the splice donor site region and can be in a region 13-16 nucleotides 3xe2x80x2 of the exon 10 splice donor site.
The invention also features an isolated polypeptide encoded by a tau nucleic acid molecule of the invention. The polypeptide contains a mutation linked to a Tau pathology. Suitable mutations are described above.
In another aspect, the invention features a transgenic non-human mammal including a nucleic acid construct and progeny thereof. The nucleic acid construct includes a regulatory element such as a brain-specific promoter (e.g., a prion gene promoter) operably linked to a nucleic acid sequence encoding a Tau polypeptide (e.g., a human Tau polypeptide). The Tau polypeptide includes a pathogenic Tau mutation and is expressed in the transgenic non-human mammal. The transgenic non-human mammal exhibits a Tau pathology (e.g., the non-human mammal develops neurofibrillary tangles), and can be a rodent such as a mouse. The mutation can be at amino acid 152, 257, 272, 280, 301, 389, or 406 of the human Tau polypeptide, e.g., substitution of a leucine residue for a proline residue at amino acid 301.
The transgenic non-human mammal further can include a nucleic acid construct that includes a regulatory element operably linked to a nucleic acid molecule encoding a human amyloid precursor protein (APP) or a human presenilin-1 protein. The human APP can include mutations at amino acids 670 and 671 e.g., substitution of an asparagine residue at amino acid 670 and substitution of a leucine residue at amino acid 671. Transgenic non-human mammals expressing a human APP and a tau polypeptide can develop neurofibrillary tangles and amyloid plaques. Such non-human mammals exhibit an increased number of neurofibrillary tangles as compared with a control transgenic non-human mammal expressing a mutant Tau polypeptide.
In another aspect, the invention features a method for identifying agents that inhibit development of a Tau pathology. The method includes administering a test agent to a transgenic non-human mammal and determining if the test agent inhibits development of the Tau pathology in the transgenic non-human mammal as compared with a corresponding transgenic non-human mammal to which the test agent has not been administered. The transgenic non-human mammal includes a nucleic acid construct, wherein the construct includes a regulatory element operably linked to a nucleic acid molecule encoding a Tau polypeptide, wherein the polypeptide includes a pathogenic Tau mutation and is expressed in the transgenic non-human mammal, and wherein the transgenic non-human mammal exhibits a Tau pathology. The mutation can be at amino acid 152, 257, 272, 280, 301, 389, or 406, as described above. The transgenic non-human mammal can develop neurofibrillary tangles.
Transgenic non-human mammal useful in the method also can express a human APP or human presenilin-1 polypeptide. Human APP can have a mutation at amino acids 670 and 671, e.g., an asparagine residue can be substituted at amino acid 670 and a leucine residue can be substituted at amino acid 671. Such a transgenic non-human mammal can develop neurofibrillary tangles and amyloid plaques. The transgenic non-human mammal can develop an increased number of neurofibrillary tangles as compared with a control transgenic non-human mammal expressing a mutant Tau polypeptide.
The invention also relates to a method for determining a diagnosis, prognosis, or risk of neurodegenerative disease in a patient. The method includes detecting a tau gene mutation in genomic DNA of the patient, wherein the mutation is linked to a Tau pathology. Mutations that are linked to Tau pathologies are described above.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used to practice the invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.